Guidelines on postoperative magnetic resonance imaging in patients operated for cryptoglandular anal fistula: Experience from 2404 scans

Table 1 Guidelines for postoperative magnetic resonance imaging in management of anal fistulas

Guidelines for postoperative MRI in management of anal fistulas
(1) Challenges in interpreting the MRI in postoperative period
(2) Timing of postoperative MRI
(3) Utility of MRI in postoperative period for anal fistula management: Checking for missed tract and confirm adequate drainage of all abscesses; Checking for new abscess/tract development; Confirming healing of internal opening
(4) Active involvement and experience of clinician in interpreting MRI scans
(5) Other advancements

MRI: Magnetic resonance imaging.

Table 2 Overview of magnetic resonance imaging scans done

Overview
Total patients = 1719	Total MRI evaluated in 1719 patients = 2404
Total patients operated = 1255	Total MRI in 1255 operated patients = 1940
	Preoperative MRI in 1255 operated patients = 1255
Patients in whom postoperative	Number of MRI done in 411 patients = 685
MRI done = 411/1255

MRI: Magnetic resonance imaging.

Table 3 Characteristics of operated anal fistula patients analyzed by magnetic resonance imaging

Parameter	Patients (n = 1255)
M/F	1078/177
Recurrent (%)	754 (60.1)
Associated abscess (%)	328 (25.7)
Multiple fistula tracts (%)	777 (61.9)
Horseshoe tract (%)	285 (22.7)
Supralevator or suprasphincteric tract (%)	162 (12.9)
Simple/complex fistulas	621/ 634
Fistula classification as per different classifications
St James’s University Hospital	I-193
	II-180
	III-150
	IV-570
	V- 162
Parks	I-375
	II-698
	III-162
	IV-0
Garg	I-265
	II-390
	III-83
	IV-355
	V- 162

Garg classification is a recently proposed classification (2017), which has been shown to correlate accurately with fistula complexity[15,16]. F: Female; M: Male.